Excessive soot from water heater

[Knauby]

While running my hot water heater on gas this weekend I noticed heavy soot accumulation over vent and side of camper. I know little about LP appliances. Any ideas on what is wrong and what is the fix?

[SmokerBill]

Bugs or cobwebs in the burner tube that mixes air with the propane might be the problem.

[arkhillbilly]

Another thought is the flame. If it is yellowish, its producing soot. Needs to be blue, with some white at the top. Not sure of the web page, but i'am sure there are things on u-tube.

[RedHorse1]

Smoker and ark are on it.

The burner might need adjusting. But my guess would be something in the burner tube blocking airflow.

[Skaling]

I'm a class A gas fitter with lots of residential/commercial experience. Not so much in RV's but the principles have to be the same. Incomplete combustion produces soot. Keeping burners and pilots cleaned and properly adjusted can reduce the amount of soot produced.
Incomplete combustion occurs when all of the fuel does not burn. Common causes are:

* Dirt on burners

* Incorrect gas orifice sizes (either too large or too small, especially critical to check as natural gas/LP conversions are made).

* Flame impinging on a cold surface (incorrectly placed artificial logs in a gas fireplace, cold cooking utensils on gas range, incorrectly designed burner and heat exchanger).

* Incorrect gas pressure (either too high or low). Can be intermittent, if gas regulator is malfunctioning, or continuous if pressure adjustments were made incorrectly.

* Air flow disturbing flame (fan blowing on burner or cracked heat exchanger in furnace).

* Insufficient oxygen in small room.

* Downdrafting of vent disturbing air flow through heating appliance (often intermittent and sporadic).

[VicS1950]

Good info above from others already.

I would add that if the unit was operating properly up until lately I would never let anyone start adjusting things until the unit is properly cleaned. People will sometimes muck around with settings before thoroughly checking for something which has changed (bugs, nesting material, leaves, dirt, and further down on the list, pressures, etc.).

FWIW. vic

[bedrck46]

The following was copied from the
2004 edition of the Atwood Water Heater Service Manual


SMOKING AND SOOTING
Gas pressure incorrect --------------------------Set pressure to a minimum of 11˝ W.C. with two or more appliances running
Poor gas supply ----------------------------------Replace gas supply
Improper pilot flame ----------------------------Clean or replace pilot orifice
Improper air adjustment ------------------------Adjust main burner air shutter approximately 1/4 open
Flame spreader mis-aligned --------------------Re-align or replace main burner
Blocked main burner ----------------------------Remove blockage
Improper main burner alignment --------------Re-align main burner, main burner orifice holder and gas valve
Blocked “U” tube --------------------------------Remove blockage


ERRATIC BURNER FLAME OR SOOTING
Low gas pressure ------------------------------------------------Set inlet pressure at a minimum 11˝ W.C. with two or more gas
appliances running
Poor gas supply --------------------------------------------------Replace gas supply
Improper air adjustment ----------------------------------------Adjust main burner air shutter approximately 1/4 way open. Flame
should be mainly blue and quiet
Poor main burner alignment ------------------------------------Adjust valve and main burner alignment
Misaligned burner flame spreader ------------------------------Align flame spreader so it is square with end of burner tube.
Blocked burner orifice --------------------------------------------Clean orifice. DO NOT enlarge orifice
Obstructed main burner------------------------------------------Clean main burner
Obstructed “U” tube ----------------------------------------------Clean “U” tube
Obstructed exhaust grille ----------------------------------------Remove obstruction

[bedrck46]

I posted the above as I had the same problem this past weekend. This was the first time I had this problem with a new (installed this past Apr/May) HW heater. I suspect that during the night one of my bottles went low/empty and the Auto Changeover Reg. switch bottles. This would relate to a low pressure problem. This may be something to look into before checking other areas.

[steveb285rks]

99% it is a spider nest in the burner tube. Pick up a small test tube brush to clean it out now and when it happens again later.

[Seann45]

https://www.youtube.com/watch?v=nSjDklZh4ws

[Hattie]

We had exactly the same symptoms not too long ago while dry-camping, so immediately turned-off the hot water heater. Turns-out the heat exchanger was cracked and we had to get it replaced under warranty. See my posting at: http://www.jaycoowners.com/forums/f1...ork-30773.html

[edatlanta]

I blow mine out with compressed air a couple of times a year or whenever it won't light. Spiders every time.

[dwdlt]

Originally Posted by edatlanta

I blow mine out with compressed air a couple of times a year or whenever it won't light. Spiders every time.

Same here. I keep a can of compressed air in my emergency kit, and if I haven't been out in a while, I blow out the burner tube just to be safe.

[Jagiven]

I had the same issue while on our last campout for the year. I rarely use the propane side of the heater, almost always the electric option. While walking at night I noticed from a distance the flame indicator light up, and the flame was fairly yellow. The water heater was only on gas for a few hours, the next morning I noticed the side of the TT was covered in soot. I have not done it yet, but will need to clean the burner tube. Most likely there is a spider nest in it. For some crazy reason spiders like propane.

[bedrck46]

I once was told by a friend that the best way to keep spiders away from the WH burner is to place fles and tick collars in the compartment. He claimed they work better than moth balls and no odor.
Only problem is they need to be replaced about every 3 to 4 months. I have never tried it and I was going to get some for the RV this year except the camper is now in storage and winterized and 80 miles away. I'll just have to make sure I cleaner the burner come spring and the try the flea and tick collars

[troutslayer]

Originally Posted by bedrck46

I once was told by a friend that the best way to keep spiders away from the WH burner is to place fles and tick collars in the compartment. He claimed they work better than moth balls and no odor.
Only problem is they need to be replaced about every 3 to 4 months.

I use the flea and tick collars in the WH compartment and refrigerator compartment. I don't know about them keeping spiders away but they do keep wasps out of there and they do need to be replaced every couple months. Moth balls are flamable.
Last year I used compressed air to blow out the flame tube but didn't have the red plastic extension nozzle tightly in place and it blew into the flame tube. That could be the cause of my black smoke